The silicon microchip is partially immersed in Dulbecco's Modified Eagle Medium (DMEM). Its electrostatic actuators are kept out of the solution.

Understanding the mesengenic process and the differentiation factors of mesenchymal stem cells is a great challenge for biologists, since it has lots of potential medical applications, particularly in cell-based therapy and tissue
engineering. This interdisciplinary work is a contribution to a project whose objective is to study the influence of mechanical strain (i.e.mechanotransduction) on the fate of these cells.

A Bio-MEMS has been previously developed for these assays. The goal of this research was to design a solution that enables a partial horizontal immersion of the microchip in the culture solution, while keeping the electrostatic

actuators dry. After a preliminary feasibility study, a setup based on the principle of the
capillary passive valves has been devised and fabricated. The porposed system uses an innovative
operating principle which can be used for several other applications and MEMS designs. In addition to technical specifications, it perfectly fulfils the restrictive biological requirements.

A preliminary characterization of the MEMS device has been achieved. It showed the proper operation of the chip in liquid and highlighted
differences in the amplitude response when the chip was partially immersed. These successful tests confirmed the good performance and reliability of the setup. Hence, assays on cells can now be considered.